The present invention relates to a drive assembly for multi-directional lateral displacement between a tool and a workpiece, suitable for use with electroerosion or other machine tools. The term "electroerosion" is intended herein to include electrical discharge machining (EDM), electrochemical machining (ECM) and electrochemical discharge machining (ECDM), all of which are known in the machining art.
In these machining processes, it is sometimes desirable to displace a tool electrode, relative to a workpiece which has undergone rough-machining, in a vertical direction (or along z axis), laterally or in a plane transverse to the latter (or along x and y axes) in a plurality of predetermined directions therein by increments, thereby finish-machining the workpiece. Such multi-directional lateral displacement may also be required when a workpiece rough-machined mechanically is to be finished by an electroerosion process and when a shaped block produced by a wire-cut EDM is to be utilized as a punch in a die-punching process whereby there should be provided an adequate clearance between the die and the punch by electroerosion. Besides such operating modes, the lateral displacement may be effected in the manner that the electrode is moved in an orbital travel path for electroerosion or another machining process. The requirement may also arise where a slanted wire electrode is displaced in wire-cut EDM to produce a tapered cut.
There have heretofore been proposed various arrangements for such multi-directional lateral displacement including one utilizing attraction or repulsion between a magnet and a set of magnetizable pieces coupled to the tool and the workpiece, respectively, or vice versa. In the latter system, the magnetic force must act at least in three or four directions and must be uniform in all directions. In the known system, however, the adjustment of a magnetic gap required to insure such multi-directional uniformity has imposed a difficulty and further the distance of displacement which must be adjusted according to a desired displacement pattern has not been readily adjustable and has been time-consuming.